The June Bootid Meteor Shower.

The June Bootid Meteor Shower is visible each year between 26 June and 2 July, typically peaking on 27 June. This meteor shower if highly unpredictable in nature, with most years producing very few meteors, but the shower occasionally having peak years, in which hundreds of meteors are visible each hour; the most recent major peak year happened in 1998 (a smaller peak was recorded in 2004), with the three peaks prior to that happening in 1927, 1921, and 1916. The shower has a radiant point (point from which the meteors appear to radiate) in the constellation of Boötes, close to the North Pole, making the shower possible to spot from anywhere in the Northern Hemisphere, but hard to see in the Southern Hemisphere. Unfortunately, this year's peak activity comes only two days before the Full Moon on 29 June, which means that good observation of the meteors may be hampered by the brightness of the Moon.

The radiant point of the June Bootid Meteor Shower. Space Weather.

Meteor showers are thought to be largely composed of material from the tails of comets. Comets are composed largely of ice (mostly water and carbon dioxide), and when they fall into the inner Solar System the outer layers of this boil away, forming a visible tail (which always points away from the Sun, not in the direction the comet is coming from, as our Earth-bound experience would lead us to expect). Particles of rock and dust from within the comet are freed by this melting (strictly sublimation, transforming directly from a solid to a gas due to the low pressure on it's surface) of the comet into the tail and continue to orbit in the same path as the comet, falling behind over time.

The Earth passing through a stream of comet dust, resulting in a meteor shower. Not to scale. Astro Bob.

The June Bootids Meteor Shower is caused by the Earth passing through the trail of comet 7P/Pons-Winnecke, where it encounters thousands of tiny dust particles shed from the comet as its icy surface is melted (strictly sublimated) by the heat of the Sun. 7P/Pons-Winnecke visits the Inner Solar System every 6.37 years, most recently in May 2021, and last came close to the Earth in 1939.

How the passage of the Earth through a meteor shower creates a radiant point from which they can be observed. In The Sky.

7P/Pons-Winnecke was discovered on 12 June 1819 by French astronomer Jean-Louis Pons, then based at Marseilles Observatory, and rediscovered by Friedrich August Theodor Winnecke at Pulkovo Observatory near Saint Petersburg. The designation 7P/Pons-Winnecke implies that it was the seventh comet discovered (7/ - strictly speaking people had been observing comets for thousands of years, but it was not until the mid-eighteenth century that it was realised that they were predictable objects that returned cyclically), that it is a periodic comet (P - again, most comets are periodic, but the term 'periodic comet' is reserved for those with periods of less than 200 years, since these can be reliably predicted), and that it was discovered by Pons and Winnecke.

7P/Pons-Winnecke immaged on 23 September 2015 from Kiev, Ukraine. The image is a single 300 second exposure, with the slightly elongate objects being stars that have moved over the course of the exposure. Alexander Baransky/Kiev Comet Station/Fachgruppe Kometen.

Comet 7P/Pons-Winnecke currently completes one orbit every 2326 days (6.37 years) on an eccentric orbit tilted at 22.3° to the plane of the Solar System, that takes it from 1.26 AU from the Sun (126% of the average distance at which the Earth orbits the Sun) to 5.61 AU from the Sun (5.61 times as far from the Sun as the Earth, and slightly outside the orbit of Jupiter). As a comet with a period of less than 20 years with an orbit angled at less than 30° to the plane of the Solar System, 7P/Pons-Winnecke is considered to be a Jupiter Family Comet.

The orbit and current position of 7P/Pons-Winnecke. JPL Small Body Database.

This orbit means that 7P/Pons-Winnecke occasionally comes close to the Earth, with the last close approach having happened on 1 July 1939, when it reached a distance of 0.11 AU from the Earth (11% of the distance between the Earth and the Sun, or 16 052 000 km). The comet will next come close to us in June 2062, when it will reach a distance of 0.17 AU from the Earth.

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The Ursid Meteor Shower.

The Ursid Meteors are expected to peak at about 4.00 pm GMT on the evening of Monday 22 December this year, with the shower being potentially visible to some extent between Monday 17 and Wednesday 26 December.  The shower is typically best seen between midnight and dawn from anywhere in the Northern Hemisphere (it is difficult, if not impossible, to view it from the Southern Hemisphere). The extent of the shower is variable, some years producing over 100 meteors per hour at its peak, others less than 10. The peak of this year's shower falls slightly after the New Moon, on 20 December, so viewing should be good, with little glare from the Moon to hinder the viewing of meteors. The meteor shower gets its name from the constellation of Ursa Minor, in which it appears to originate.

The radiant (apparent point of origin) of the Ursid Meteors. BBC Science Focus Magazine/PA.

Meteor streams are thought to come from dust shed by comets as they come close to the Sun and their icy surfaces begin to evaporate away. Although the dust is separated from the comet, it continues to orbit the Sun on roughly the same orbital path, creating a visible meteor shower when the Earth crosses that path, and flecks of dust burn in the upper atmosphere, due to friction with the atmosphere.

The Earth passing through a stream of comet dust, resulting in a meteor shower. Not to scale. Astro Bob.

The Ursid Meteor Shower is caused by the Earth passing through the tail of Comet 8P/Tuttle, and encountering dust from the tail of this comet. The dust particles strike the atmosphere at speeds of over 200 000 km per hour, burning up in the upper atmosphere and producing a light show in the process. The Earth does not need to pass close to Comet 8P/Tuttle for the meteor shower to occur, it simply passes through a trail of dust from the comet's tail that is following the same orbital path. Comet 8P/Tuttle visits the Inner Solar System once every 13.6 years, last doing so in 2021.

How the passage of the Earth through a meteor shower creates a radiant point from which they can be observed. In The Sky.

Comet 8P/Tuttle was discovered by Horace Parnell Tuttle on 5 January 1858. The designation 8P/Tuttle indicates that it was the eighth comet discovered (people have known about comets for thousands of years, but it was only realised that they were objects orbiting the Sun, which could be repeatedly observed and predicted, in the mid-eighteenth century), that it is a Periodic Comet (comet with an orbital period of less than 200 years) and that it was discovered by Horace Parnell Tuttle.

Comet 8P/Tuttle imaged from Weißenkirchen in der Wachau in Austria on 30 December 2007. Michael Jäger/Spaceweather.

Comet 8P/Tuttle has an orbital period of 4972 days (13.6 years) and a highly eccentric orbit tilted at an angle of 55.0° to the plain of the Solar System, that brings it from 1.03 AU from the Sun at closest perihelion (103% of the distance between the Earth and the Sun) to 10.4 AU from the Sun at aphelion (10.4 times as far from the Sun as the Earth or slightly outside the orbit of the planet Saturn). As a comet with a period of less than 20 years, 8P/Tuttle is considered to be a Jupiter Family Comet.

The calculated orbit and position of 8P/Tuttle and the planets of the Inner Solar System at 4.00 pm on Monday 22 December 2025.  JPL Small Body Database.

This means that 8P/Tuttle has occasional close encounters with the Earth, with the last thought to have happened in January 2008 and the next predicted in December 2048. The comet also has occasional close encounters with the planets Jupiter, which it last came close to in December 1995 and is next predicted to pass in September 2078, and Saturn, which it last came close to in February 1930 and is expected to pass again in February 2107. Objects which make close passes to multiple planets are considered to be in unstable orbits, and are often eventually knocked out of these orbits by these encounters, either being knocked onto a new, more stable orbit, dropped into the Sun, knocked out of the Solar System or occasionally colliding with a planet. 

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The Southern Delta Aquariid Meteor Shower.

The Southern Delta Aquariid Meteor Shower is visible between roughly 12 July and 23 August each year, and is expected to peak on 30 July this year, producing up to 25 meteors per hour. Best viewing this year is predicted to be between 2.00-3.00 am (this will be in local time wherever they are viewed from, as the time reflects the orientation of the planet to the rest of the Solar System) and dawn, when the radiant point of the shower (point from which the meteors appear to radiate), which is close to the star Delta Aquari (hence the name) will be highest in the sky. This year the peak of activity will fall slightly before the first quarter moon on 1 August, and the Moon will be in the constellation of Virgo, making it reasonably distant from Delta Aqaurius in the sky, and setting before midnight, so that it should not interfere with viewing of the peak of the meteor shower.

The radiant point of the Delta Aquariid Meteors. David Dickinson/Starry Night/Universe Today.

Meteor streams are thought to come from dust shed by comets as they come close to the Sun and their icy surfaces begin to evaporate away. Although the dust is separated from the comet, it continues to orbit the Sun on roughly the same orbital path, creating a visible meteor shower when the Earth crosses that path, and flecks of dust burn in the upper atmosphere, due to friction with the atmosphere.

The Earth passing through a stream of comet dust, resulting in a meteor shower. Not to scale. Astro Bob.

The Southern Delta Aquariids are thought to be caused by the Earth passing through the trail of Comet 96P/Machholz, where it encounters thousands of tiny dust particles shed from the comet as its icy surface is melted (strictly sublimated) by the heat of the Sun. 96P/Machholz is a short period, Jupiter Family Comet, crossing our orbit every 5.24 years, but the trail of particles shed by it forms a constant flow.

How the passage of the Earth through a meteor shower creates a radiant point from which they can be observed. In The Sky.

96P/Machholz was discovered by amateur astronomer Donald Machholz from Loma Peak in California; the name 96P/Machholz implies that it was discovered by Machholz and was the 96th periodic comet discovered (a periodic comet is a comet which orbits the Sun in less than 200 years). 

The orbit and current position of Comet 96P/Machholz. JPL Small Body Database.

96P/Machholz has an orbital period of 1929 days (5.28 years) and a highly eccentric orbit tilted at an angle of 58.5° to the plain of the Solar System, that brings it from 0.12 AU from the Sun at perihelion (12% of the distance between the Earth and the Sun, considerably inside  the orbit of Mercury, and closer to the Sun than any other known periodic comet); to 5.94 AU from the Sun at aphelion (5.94 times as far from the Sun as the Earth or slightly more than the distance at which Jupiter orbits). As a comet with a period of less than 20 years, 96P/Machholz is considered to be a Jupiter Family Comet.

Image of 96P/Machholz close to the sun taken by the Solar and Heliospheric Observatory on 8 January 2002. NASA/ESA/Solar and Heliospheric Observatory.

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The Ursid Meteor Shower.

The Ursid Meteors are expected to peak at about 10 pm GMT on the evening of Sunday 22 December this year, with the shower being potentially visible to some extent between Sunday 17 and Monday 26 December.  The shower is typically best seen between midnight and dawn from anywhere in the Northern Hemisphere (it is difficult,if not impossible, to view it from the Southern Hemisphere). The extent of the shower is variable, some years producing over 100 meteors per hour at its peak, others less than 10. The peak of this years shower coicides with the Third Quarter Moon, also on 22 December, so viewing may be somewhat impaired, as glare from the Moon can hinder the viewing of meteors. The meteor shower gets its name from the constellation of Ursa Minor, in which it appears to originate.

The radiant (apparent point of origin) of the Ursid Meteors. BBC Science Focus Magazine/PA.

Meteor streams are thought to come from dust shed by comets as they come close to the Sun and their icy surfaces begin to evaporate away. Although the dust is separated from the comet, it continues to orbit the Sun on roughly the same orbital path, creating a visible meteor shower when the Earth crosses that path, and flecks of dust burn in the upper atmosphere, due to friction with the atmosphere.

The Earth passing through a stream of comet dust, resulting in a meteor shower. Not to scale. Astro Bob.

The Ursid Meteor Shower is caused by the Earth passing through the tail of Comet 8P/Tuttle, and encountering dust from the tail of this comet. The dust particles strike the atmosphere at speeds of over 200 000 km per hour, burning up in the upper atmosphere and producing a light show in the process. The Earth does not need to pass close to Comet 8P/Tuttle for the meteor shower to occur, it simply passes through a trail of dust from the comet's tail that is following the same orbital path. Comet 8P/Tuttle visits the Inner Solar System once every 13.6 years, last doing so in 2021.

How the passage of the Earth through a meteor shower creates a radiant point from which they can be observed. In The Sky.

Comet 8P/Tuttle was discovered by Horace Parnell Tuttle on 5 January 1858. The designation 8P/Tuttle indicates that it was the eighth comet discovered (people have known about comets for thousands of years, but it was only realised that they were objects orbiting the Sun, which could be repeatedly observed and predicted, in the mid-eighteenth century), that it is a Periodic Comet (comet with an orbital period of less than 200 years) and that it was discovered by Horace Parnell Tuttle.

Comet 8P/Tuttle imaged from Weißenkirchen in der Wachau in Austria on 30 December 2007. Michael Jäger/Spaceweather.

Comet 8P/Tuttle has an orbital period of 4972 days (13.6 years) and a highly eccentric orbit tilted at an angle of 55.0° to the plain of the Solar System, that brings it from 1.03 AU from the Sun at closest perihelion (103% of the distance between the Earth and the Sun) to 10.4 AU from the Sun at aphelion (10.4 times as far from the Sun as the Earth or slightly outside the orbit of the planet Saturn). As a comet with a period of less than 20 years, 8P/Tuttle is considered to be a Jupiter Family Comet.

The calculated orbit and position on 21 December 2024 of 8P/Tuttle.  JPL Small Body Database.

This means that 8P/Tuttle has occasional close encounters with the Earth, with the last thought to have happened in January 2008 and the next predicted in December 2048. The comet also has occasional close encounters with the planets Jupiter, which it last came close to in December 1995 and is next predicted to pass in September 2078, and Saturn, which it last came close to in February 1930 and is expected to pass again in February 2107. Objects which make close passes to multiple planets are considered to be in unstable orbits, and are often eventually knocked out of these orbits by these encounters, either being knocked onto a new, more stable orbit, dropped into the Sun, knocked out of the Solar System or occasionally colliding with a planet. 

See also...